1. Field of the Invention
The present invention relates generally to screening assemblies for filtering irrigation water to remove particulate matter from the water. In particular, the present invention relates to a screening assembly that uses a rotating drum-shaped screen with a self-cleaning feature to filter irrigation water.
2. Description of the Related Art
Centrifugal pumps and turbine pumps are commonly used to pump water out of outdoor pits, reservoirs, streams, rivers, ponds, lagoons, and the like, especially for irrigation purposes. Centrifugal pumps are often located above a water level of the water source and use a suction pipe or hose to draw water out of the water source to feed the pump. Turbine pumps have impellers placed below the water level and are usually fed by gravity flow of the water. Screens are typically used to prevent debris, sand and other objects from being sucked into the suction pipe for a centrifugal pump or from being drawn into the impellers of a turbine pump during operation.
Self-cleaning screens have been developed to prevent plugging by debris being drawn to the screen during pumping. An example of a self-cleaning screen is provided in U.S. Pat. No. 6,270,669 issued to Bauer. Another example of a self-cleaning screen is described in the Applicant's U.S. Pat. No. 7,670,482 and marketed by the Applicant under the proprietary name RIVERSCREEN™. These known products provide rotary self-cleaning drum strainers having a means for cleaning debris from a drum as the drum rotates during operation of the pump. The filtered water passing into the drum is drawn from the interior of the drum by a suction pipe or gravity fed pipe for delivery to an irrigation system.
The Applicant's '482 patent describes a self-cleaning screen that is designed to operate in shallow water with less than half of the screen submerged. For example, the '482 patent can be operated with only the lower quarter of the screen submerged, and is particularly suitable for use in rivers and streams with shallow, flowing water conditions. The screen is driven to rotate about its axis by the driving force of water flowing past the drum, or by a power drive system that sprays water against the outer surface of the drum during pump operation. A cleaning spray is also provided in the '482 patent by a conduit and spray nozzles positioned within the drum for spraying water in a radially outward direction to dislodge debris from the drum.
There is a need in the industry for an improved self-cleaning screen assembly that is particularly suitable for pumping conditions in which more than half of the screen is submerged.